Synthesis And Application Of Near-infrared Cyanine Fluorescence Dyes

As its spectra in the near-infrared (NIR) region, heptamethine cyanine dyes haveattracted immense interest in the fields of bioanalysis and angiography. Herein, aheptamethine cyanine dye (4) was synthesized. And then ten other dyes were achievedby nucleophilic reaction at the chlorine of the dye (4).Their photochemical properties were investigated. The spectroscopic propertiesof dye (5) were different from the dye with aniline in the middle position. It indicatedthat a tiny chang in structure could lead to great difference in spectra properties. Itwas also found that different substitutions (piperazine, morpholine) at the centralposition of the dyes lead to diverse optical properties. Besides, the modification ofheterocycles at the middle position had great influence on the spectroscopic properties.The synthesized dyes (6)-(14) had large stokes shift, especially in DMF, which makethem capable for use in bioanalytical purposes. There existed an ICT process in thesedyes. Besides, the introduction of another quaternary ammonium salt structure canincrease the water solubility of the dyes.After the investigation of the spectroscopic properties, we found that thesefluorescent dyes exhibited a wealth of spectroscopic response toward the change ofpH value. The dyes substituted with piperazine are more sensitive, under acidic andbasic conditions, the dyes showed obvious changes in the absorption and fluorescencespectras, and can be used as pH probes.Dyes (6-10) were applied in the preparation of fluorescent PS microspheres bythe absorption method. And the NIR fluorescent microspheres were preparedsuccessfully. Their photochemical properties, as well as the pH-dependent opticalcharacters were investigated. They showed high sensitivity to the changes of pHvalues which were achieved from the parent dyes, more important, the microspherewas able to work in aqueous media, which is highly valuable for use in biologicalapplications.Imidazole was taken as the recognize group, a chemosensor was synthesized, andhad been indicated to be a fluorometric probe for fluoride anion with good sensitivityand high selectivity after the studies of its spectroscopic properties. This probeshowed obvious changes in UV absorption and fluorescence spectra in the presence offluoride anions.Based on the ring-opening reaction of spirocyclic Rhodamin B with metal ions, a probe for the detection of Cu2+was designed and synthesized. After the investigationof its spectra properties, the probe was found to be a good probe with high selectivityand good sensitivity. And the further studies revealed that its fluorescence recoveredafter the addition of cyanide.